This invention relates to a container coupling device for preventing stacked containers from moving or being displaced in the back-and-forth and right-and-left directions.
Generally, in transporting many containers by ship, containers are stacked on hold floors or on the deck and upper and lower containers are coupled together by a container coupling device to prevent displacement of the containers.
Stacked containers have their outer peripheral corners guided by vertically extending guides, so that they have a relatively small tendency to incline in the vertical direction. Thus, upper and lower containers are coupled together by container coupling devices for preventing displacement in the back-and-forth and right-and-left directions.
As a container coupling device for preventing displacement of containers, one shown in FIGS. 6 and 7 is known. This container coupling device is integrally provided with a support shaft 22 on the top surface of a flange 21 arranged between upper and lower containers C1 and C2. An upper positioning protrusion 23 which is inserted into an engaging hole a1 formed in a bottom corner fitting A1 of the upper container C1 is provided so as to be rotatable about the support shaft 22. At the top end of the support shaft 22, an engaging member 24 is integrally provided and has its two ends engageable with the peripheral edge of the engaging hole a1 of the bottom corner fitting A1.
On the bottom surface of the flange 21, a lower positioning protrusion 25 is integrally provided and can be inserted into an engaging hole a2 formed in a top corner fitting A2 of the lower container C2.
To position containers using such container coupling devices, the position of the upper positioning protrusion 23 is adjusted so that the engaging member 24 is received within the outer periphery of the upper positioning protrusion 23 by rotating the upper positioning protrusion about the support shaft 22. Then, the upper positioning protrusion 23 is inserted into the engaging hole a1 in the bottom corner fitting A1 of the upper container C1, and both ends of the engaging member 24 are brought into engagement with the peripheral edge of the engaging hole a1 in the bottom corner fitting A1 by rotating the flange 21 relative to the upper positioning protrusion 23 to mount the container coupling device to the bottom surface of the upper container C1.
After mounting the container coupling device, the upper container C1 is stacked on the lower container C2 loaded beforehand to insert the lower positioning protrusion 25 into the engaging hole a2 in the top comer fitting A2 of the lower container C2, thereby preventing displacement of the upper and lower containers C1 and C2 by the engagement of the positioning protrusions 23 and 25 in the respective engaging holes a1 and a2.
In this conventional container coupling device, since the upper positioning protrusion 23, which is adapted to be inserted into the engaging hole a1 in the bottom comer fitting A1 of the upper container C1, is supported so as to be rotatable about the support shaft 22, if the upper container C1 inclines with the upper and lower containers C1 and C2 positioned by the container coupling device, a load will act on the support shaft 22.
Since the support shaft 22 extends through the positioning protrusion 23, there is a limit to an increase in the outer diameter of the support shaft 22. Since a load due to inclination of the upper container is borne by the support shaft 22, which is small in outer diameter and weak in the mechanical strength, there is a fear that the support shaft 22 may break. Thus one problem is poor durability.
Also, with the container coupling device mounted to the bottom corner fitting A1 of the upper container C1, since the engaging member 24, which engages the peripheral edge of the engaging hole a1 in the comer fitting A1, is pivotable relative to the upper positioning protrusion 23, when the upper container C1 is lowered to stack it on the lower container C2, if the lower positioning protrusion 25 abuts an obstacle and turning force is imparted thereto, there is a danger that the engaging member 24 will rotate out of engagement with the peripheral edge of the engaging hole a1 such that the container coupling device will fall.
An object of this invention is to improve durability and safety of a coupling device for preventing displacement of containers in the back-and-forth and right-and-left directions.
According to this invention, there is provided a container coupling device comprising a flange arranged between upper and lower containers, and positioning protrusions integrally provided on top and bottom surfaces of the flange for preventing displacement of the upper and lower containers in the back-and-forth and right-and-left directions by being inserted into engaging holes formed in opposed corners of the upper and lower containers. The upper positioning protrusion has in the center of its top surface a downwardly extending inserting hole. A rotary shaft is inserted in the inserting hole so as to be rotatably supported. An engaging member is provided on the top end of the rotary shaft so as to be engageable and disengageable relative to the peripheral edge of the engaging hole of the upper corner fitting. A turning amount limiting mechanism sets the turning range of the rotary shaft for rotation between an engaged position in which ends of the engaging member protrude outwardly from the sides of the upper positioning protrusion and a disengaged position in which the entire engaging member is received within the outer peripheral surface of the upper positioning protrusion.
By integrally providing the upper positioning protrusion on the flange, with the upper and lower containers positioned, if the upper container inclines, the load due to the inclination is borne by the upper positioning protrusion which is integral with the flange. Thus, it is possible to bear an extremely large load on the upper positioning protrusion, so that a coupling device superior in durability can be obtained.
Also, in a mounted state in which both ends of the engaging member engage the peripheral edge of the engaging hole formed in the bottom corner fitting of the upper container, during transfer for e.g. stacking the upper container, even if an obstacle collides against the lower positioning protrusion and a turning force is imparted to the coupling device, the engaging member will not turn in the disengaging direction. Thus, it is possible to avoid danger due to a fall of the coupling device.
Also, if a spring for imparting a turning force to the rotary shaft in such a direction that the engaging member engages the peripheral edge of the engaging hole is provided, by inserting the upper positioning protrusion into the engaging hole of the bottom corner fitting of the upper container and releasing the operating force for turning the rotary shaft, the engaging member will turn due to the resilience of the spring and its ends will automatically engage the peripheral edge of the engaging hole. Thus, it is possible to reliably mount the container coupling device to the bottom corner fitting in a short time.
As the turning amount limiting mechanism, a through hole communicating with the inserting hole is formed in the sides of the lower positioning protrusion, and a lever is mounted to the rotary shaft at a position opposite the through hole, thereby limiting the turning amount of the rotary shaft by the abutment of the lever on both inner peripheral sides of the through hole.
In the turning amount limiting mechanism, by forming the recesses which can accommodate the lever in both sides thereof, it is possible to prevent the lever from inadvertently turning even if the lever collides against an obstacle. Thus it is possible to reliably retain the engaging member in a position in which it engages the peripheral edge of the engaging hole and thus to further increase safety.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: